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NEET
Exam
NEET
Subject
Physics
Chapter
Work, Power and Energy

NEET · Physics · Work, Power and Energy

A block of mass 2 ~kg is free to move along the x -axis. It is at...

A block of mass 2 kg2 \mathrm{~kg} is free to move along the xx-axis. It is at rest and from tt =0=0 onwards it is subjected to a time-dependent force F(t)F(t) in the xx direction. The force F(t)F(t) varies with tt as shown in the figure. The kinetic energy of the block after 4.5 s4.5 \mathrm{~s} is A block of mass 2 ~kg is free to move along the x -axis. It is at rest and from t =0 onwards it is subjected to a

Options

  1. A4.50 J4.50 \mathrm{~J}
  2. B7.50 J7.50 \mathrm{~J}
  3. C5.06 J5.06 \mathrm{~J}
  4. D14.06 J14.06 \mathrm{~J}

Correct answer

C. 5.06 J5.06 \mathrm{~J}

Step-by-step solution

Area under FF - tt graph = momentum =P=2km∴k=A22m(A= net area of  F−t graph) ={(4×32)−(1.5×22)}22×2=5.0625 J\begin{aligned}&=P=\sqrt{2 k m}\\ & \therefore \quad k=\frac{A^2}{2 m}\\ &(A=\text{ net area\text{ of } }F-t \text{ graph) }\\ &=\frac{\left\{\left(\frac{4 \times 3}{2}\right)-\left(\frac{1.5 \times 2}{2}\right)\right\}^2}{2 \times 2}=5.0625 \mathrm{~J} \end{aligned}\therefore$ The correct option is (c).
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